/*
Copyright (c) 2007. Victor M. Alvarez [plusvic@gmail.com].

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#include "hash.h"

#define ROTATE_INT32(x, shift) ((x << (shift % 32)) | (x >> (32 - (shift % 32))))

unsigned int byte_to_int32[]  =
{
    0xC3113E7F,0x4C353C5F,0x7423810B,0x258D264E,0xDAD39DED,0x75D0B694,0x98CE1216,0x93334482,
    0xC5C48EA5,0xF57E0E8B,0x5D7F3723,0x396B1B24,0xA8883D9F,0xB2A74A00,0xF8E171AE,0x3F01FBAB,
    0x5C1840CB,0xDDD833C4,0x8D8CCA34,0x32EF223A,0x1A05B871,0x9A9B6BFC,0x50406A0C,0xE7E1FC04,
    0x5E07D7F6,0x80B83660,0x20892A62,0xB2C6FEA6,0x6CEC7CAA,0x182F764B,0x3B0353E7,0x57FC2520,
    0x4B6812D4,0xACB654E4,0x23C75C04,0xB1DCD731,0xE3AF0733,0xF2366D39,0xC729671B,0xFF3BE6F2,
    0xABA37E34,0x3CDAFA38,0xAAD18D03,0xA8D35345,0x08E9A92C,0xF9324059,0x42D821BE,0x1BC152DD,
    0x5588811C,0x874A1F9A,0x6E83E9CD,0xDA6F3AF8,0x965D4670,0xA7A565C0,0x68D8A9AF,0xFC8FD8FD,
    0x8FF99FF9,0x4C9B42AE,0x2D066A8D,0x4D1802F7,0x557032B2,0x12BCF371,0xDC29D5AE,0x72EA361F,
    0xE2835B0B,0xDFC58966,0x13B0F34D,0x3FA02BCD,0xBF282E3D,0x7DC877F5,0xF4848A32,0x861E35F5,
    0x7FFA0D7F,0x515F2E4E,0x6B235D5C,0x55F46E24,0x35AD2C99,0x072654A8,0x05163F0F,0x9317B11A,
    0xAED1FC10,0x989444F0,0xDB3E1814,0x446C0CF1,0x660BF511,0x2F227D3A,0xFDBA0539,0xC649E621,
    0x5204D7CE,0x5FA386D0,0xE5F22005,0x97B6C8A1,0x4AB69EC2,0x5C7CA70D,0x39A48EC6,0x7BACF378,
    0x8D0ED3D1,0xE39DE582,0xC5FBE2AB,0x37E3D2D0,0x06F44724,0x73144144,0xBA57E905,0xB05B4307,
    0xAEED8D97,0xA68CCAC4,0xE30DA57E,0xED0F194B,0x8C2B9B7A,0x814575D5,0x79588493,0x81D3712A,
    0x3FA892F2,0x80F0BB94,0x44EAF51A,0x4E05F1D4,0xFC69F858,0x775E8D60,0x22B20DD7,0x170A87EA,
    0x1077DE52,0x3D5EC9FB,0x0B6EB1E5,0xF2F9CCAF,0xA76C7DEB,0xD8C2D873,0xF438C592,0x6239FEEC,
    0x26D3D2A9,0x30F6FADF,0x4B2984CC,0x6257F3DA,0x0E0583E2,0x143E5E61,0xBB2732BF,0x9653217A,
    0x027A84EA,0x95C9AE8B,0x89B8B82B,0x9F286485,0x29F622FE,0x52A3196B,0x8392D95F,0x33A79167,
    0xF5DEE92A,0x6E397DB9,0x11931C01,0x8DD2CD3B,0xF9E6003D,0xAB955AF4,0xD38725F9,0xDCF6F8AE,
    0x7667A958,0xE67AD995,0xB7CF979A,0xD88EBE5B,0x5BA889F0,0x078BDD90,0x447238F9,0x3135F672,
    0x187B95A8,0x0B7D5751,0xACD59D2A,0x9C5D1929,0x579E5022,0xEA90499B,0x59901800,0x82237DB5,
    0x7A375509,0xACA9A22A,0xEC96E649,0x69339DB0,0x081D0D9B,0xD72FB8B9,0xA4184653,0xC057321D,
    0xED19CAB9,0xB48F1E3E,0xB9DAC51E,0xDAED2FC7,0x7598CBBD,0x208DF346,0x044BE6EC,0x1C63E6EB,
    0xA15F64C1,0xE024A061,0x68309584,0x0758A68D,0xF274E9AE,0x0ABEA0CC,0xED4FB267,0x63D6EC46,
    0x9F28E026,0xF0694A17,0x9D6E9115,0xC4600FAD,0x5B121E99,0xD6B4A13B,0xF5364B8A,0x8514B254,
    0x0182F8DD,0xDB09F90B,0x78C70B32,0xD8EC3B02,0x8CD7084D,0xA4439838,0x72F35A3D,0x200B48A5,
    0xE2351444,0xA5552F5F,0xD8C1E746,0x0FE5EF3C,0xB6A47063,0x61F4E68B,0x08FED99B,0x7E461445,
    0x43CB8380,0x28BA03C8,0x21A7A2E2,0x43437ED6,0x2A9E6670,0x89B4A106,0xC6C2F4EE,0x9C4063CC,
    0x2FA0DF6C,0xB54DC409,0xCF01538F,0x616431D7,0x02CB0E4D,0x44FFF425,0xAAD5188E,0x0742E9BC,
    0xFFF41353,0x130F0A15,0x787BDC10,0x4A327B72,0x702989F7,0x5F704798,0x8156A1BB,0x2BCA3E74,
    0x1911A8C4,0x5E1F27D3,0x07949DC7,0xF24C2056,0xB4299EE6,0x9C7045D9,0xA8BF6307,0x7454AAD2,
    0x256425E5,0xD87DEF67,0xCFE95452,0xE7548DF7,0xA84956C7,0xD8402C60,0xCFBD0373,0x6B6CDAFE
};


unsigned int hash(unsigned int seed, const unsigned char* buffer, int len)
{
    int i;
    unsigned int result = seed;

    for (i = len - 1; i > 0; i--)
    {
        result ^= ROTATE_INT32(byte_to_int32[*buffer], i);
        buffer++;
    }

    result ^= byte_to_int32[*buffer];
    return result;
}


unsigned int hash_update(unsigned int hash, unsigned char new, unsigned char old, int len)
{
    return ROTATE_INT32(hash, 1) ^ ROTATE_INT32(byte_to_int32[old], len) ^ byte_to_int32[new];
}

